In our industrialized society it is not unusual to find instances wherein larger molecule liquids have been mixed with water. For example, bilge water typically comprises a mixture of oil with water, as does typical liquid waste collections from automotive repair and wash facilities, machine shops, metal stamping plants, and any number of industrial or repair facilities wherein liquids such as oils, coolants, antifreeze or the like are may be commingled in use or collection with water.
With the increased awareness of society for the environment, there has been an increasing need for means to separate such larger molecule liquids and water mixtures so that clean water can be returned to the environment while the larger molecule liquids can be recovered and recycled for the further use and benefit of mankind. Federal, state and local governments, in response to this increased awareness of society, have promulgated and instituted new laws concerning the handling and disposal of such mixtures, particularly oil/water mixtures, such that it has become increasingly economically desirable to separate out as much water as possible from such mixtures conveniently at the site of commingling, to reduce the volume of liquid to be otherwise collected for recycle or disposal off site. Thus, there is an increasing need for a convenient, portable device which will effectively and economically separate water from larger molecule liquids, particularly petroleum oils, to provide a reduced volume for collection, recycle and disposal at remote sites.
One device which has been proposed and is generally commercially available for the separation of such mixtures is the ultrafiltration device. In a typical ultrafiltration device a fluid containing mixture, such as oils with water is directed, under typically low pressure, to an ultra-filtration membrane. The ultra-filtration membrane comprises microscopic hydrophilic pores which will allow water to pass through the membrane but resist the passage of the oil molecules. Such selective activity is a function of the membrane, achieved through a combination of membrane characteristics including pore size, liquid contact angle and liquid surface tension. The membrane is typically arranged in a cross flow configuration wherein a feeds-from a water/oil mixture flows across the ultrafiltration membrane in such manner that the oil component of the mixture does not flow through the membrane but a portion of the water in the mixture will permeate the membrane at a low but acceptable pass-through rate. Thus, water flowing through the membrane comprises essentially no oil and can be recovered or wasted, in many instances without further treatment, while the treated mixture which does not permeate the membrane has an increased oil to water ratio. Typically the treated oil mixture, having an increased oil to water ratio, is returned to the feed mixture and is continually recycled in mixture with the feed mixture until the amount of water in the water/oil feed mixture has been significantly reduced.
Ultrafiltration devices of the type above described have typically been cumbersome units that require costly tending by the operator during the separation process to avoid harm to the membranes. Generally such prior art devices require extensive and complex disassembly procedures for routine cleaning and/or maintenance and as a result such units have not enjoyed a level of commercial success that might otherwise be expected. Such low pressure devices of the prior art also typically require about 24 hours or more to separate enough water from a 190 Liter container containing a typical 90:10 (water:oil) mixture to achieve a significantly concentrated typical 50:50 (water:oil) mixture while attaining an essentially oil free water waste containing less than about 50 ppm of oil.
Various improved ultrafiltration devices are disclosed in U.S. Pat. Nos. 4,994,184, 5,069,780 and 5,075,002 which utilize a unique combination of components that provide increased efficiency in a low pressure ultrafiltration process and significantly reduce the time required to obtain a satisfactory water:oil mixture and provide an essentially oil free waste. Though such improved devices have enjoyed commercial success, there is a continuing desire to further reduce processing time, save energy costs associated with the process and resolve various of the problems associated with typical pre-filter requirements.
It is an object of the instant invention to provide a portable ultrafiltration device, capable of separating water from larger molecule liquids such as oils, coolants, antifreeze and the like, to attain water waste containing less than about 50 ppm of the larger molecule contaminant that is simplified in operation and disassembly, provides higher pressures along the ultrafiltration membrane to assist in decreasing processing time and is internally protected from harm to costly membranes.
It is a further object of the invention to provide an improved feed mixture pick-up tube comprising a self-cleaning pre-filter means.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part may be obvious from the description of the invention that follows, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.